THE MiltF.UIIM.DRX RKM'TIOS 205 



roat'tioiis, it was assumed that the antigen was digested; but, as with 

 the preeipitiii and anaphylaxis reactions, evidence was found by 

 iiuuierous observers tiiat not the antigen but the proteins of the im- 

 mune serum are the chief or sole source of the cleavage products. For 

 some reason, liard to explain, it has always been referred to as if it 

 were the result of the formation of specific enzymes which attacked the 

 antigen, in spite of the repeated demonstration that sera giving posi- 

 tive reactions can be inactivated by heat and reactivated by normal 

 jserum,^®^ thus throwing it into the class of amboceptor-complement 

 reactions, with which it agrees in principle. 



Having been introduced first as a method for diagnosing pregnancy, 

 on the principle that in pregnancy the chorionic cells of the placenta 

 enter the maternal circulation and as foreign proteins cause the forma- 

 tion of specific "defensive ferments," it was at once taken up as a 

 clinical procedure, and as a result an enormous literature on this 

 reaction was rapidly produced. Much of this represents highlj- un- 

 critical work, largely from workers not trained or experienced in 

 immunological principles, and hence it is not profitable to review it 

 in extenso here. Abderhalden's own views are given in full in his 

 monographs """ and there exist numerous critical reviews.^*"^ The 

 status of the reaction at this writing seems to be as follows : 



Animals, or man, after having foreign proteins of any sort enter 

 the blood stream, may, and commonly do show an altered condition 

 f)f their serum, whereby when their serum is incubated with the anti- 

 g:en under suitable conditions very minute quantities of the products 

 of protein cleavage may be set free, and recognized when dialyzed 

 away from the digesting mixture ; or, a measurable change in optical 

 rotation of the digestion mixture occurs. However, perfectly normal 

 sera may at times cause a similar proteoh'sis, usually but not always 

 less than with the immune serum. 



The digestion seems to involve chiefly the serum proteins rather 

 than the antigen, although under certain conditions there may be 

 some digestion of the antigen. Bronfenbrenner holds that the en- 

 zymes exhibit no selectivity, digesting both the antigen and the serum 

 impartially.^*"* 



Apparently the digestion is accomplished by serum complement, 

 or at least normal serum enzymes, rather than by any new-formed 

 specific enzyme, although enzymes set free from the tissues have been 

 held responsible by some. 



39a See Stephan, Miinch. med. Woch.. 1914 (61), SOI: Ilrtuptmann, ibid., p. 

 1167; Betteneourt and !Menezes, Conipt. Rend. Soc. Biol., 1!)1G (77), 162. 



39b Emil Abderhalden, "Scluitzfermente des tierisclien Orpanismus." 



39c See Wallis, Quart. Jour. Med., 1016 (9), 138; Bronfenbrenner, Jour. Lab. 

 Clin. Med., 1915 (1), 79; 1916 (1), 573. Hulton, .Jour. Biol. Chcm., 1916 (25), 

 163. 



39d Supported by Smitb and Cook, .Jour. Infect. Dis., 1916 (18), 14. De Waele 

 states tbat it is the serum globulin that is digested (Conipt. Rend. Soc. Biol., 1914 

 (76), 627). 



